Turret control mechanism



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T. L. HALLENBECK TURRET CONTROL MECHANISM Feb. 17, 1953 Flled May 16,1947 we m B 3 b m 4 t n 00% h an M m A S 4 0 fim T. L. HALLENBECK TURRETCONTROL MECHANISM Feb. 17, 1953 Flled May 16, 1947 Patented Feb. 17,1953 TURRET CONTROL MECHANISM Thomas L. Hallenbeck, Toledo, Ohio,assignor to Baker Bros. 1110., Toledo, Ohio, a corporation of OhioApplication May 16, 1947, Serial No. 748,633

8 Claims. 1

This invention relates to an apparatus for controlling mechanism andmore especially to an apparatus for regulating or controlling the speedof an electrically energized. motor especially adapted for driving heavyloads.

The invention comprehends the provision of a driving means or system foroperating mechanism whereby the speed of the motor may be controlledthrough the. employment of fluid resistance.

The invention embraces the provision of a drive for mechanism utilizingan induction motor of a. type having high slip, high torque characteristics. wherein the operation of the motor may be controlledthrough the control of fluid flow through a fluid pump connected withthe motor.

An. object of the invention resides in the provision of a driving meansfor a mechanical ele ment wherein it is desirable to. periodically startand stop the element in a comparatively short period of time and whereinthe drive means is arranged to move the mechanical element successivelyto fixed stations or positions without injury to the indexing orpositioning mechanism.

Another object of the invention resides in the provision of a drivingmeans for a relatively movable machine tool work supporting table ormachine element of considerable weight wherein the driving means iscontrolled by fluid resistance acting to resist the inertia of themoving work supporting table so as to quickly bring the same to aposition of rest.

Another object of the invention is the provision of a drivingv andcontrolling means for a movable-machine element wherein a high torque,high slip induction motoris. connected to the machine element and to afluid pump, the latter being provided wtih fluid flow control orregulating' means arranged whereby fluid resistance regulates orcontrols the motor speed providing a simple and effective means forrapidly reducing the speed of or; stopping the motorand element driven.thereby.

Further objects and advantages are within the scope of'this inventionsuch as relate to the arrangement, operation and function of the relatedelements of the structure, to various details of construction and tocombinations of parts, elements' per se,' and to economics ofmanufacture and numerous. other features as will be apparent from aconsideration of the specification and drawing of a; form of the.invention, which may be preferred, in which:

Figure l is a front elevation view of a machine tool embodying a form ofmy invention;

Figure 2 is a top plan view showing a portion of the work supportingtable of the machine, certain parts being broken away and others insection for purposes of illustration;

Figure 3 is a vertical sectional View takenv substantially on the line3-3 of Figure 2;

Figure 4 is a vertical sectional view taken substantially on the line4-4 of Figure 2;

Figure 5 is a plan view illustrating a modified form of table indexingor positioning mechanism, the supporting frame therefor being shown insection;

Figure 6 is a sectional view through a fluid reservoir showing a pumpconstruction and solenoid controlled fluid flow regulating means;

Figure 7 is a diagrammatic view illustrating the functioning of pump andfluid flow valve means embodied in the form of the invention illustratedin Figures 2 and 3;

Figure 8 is a diagrammatic view similar to Figure 7 illustrating thefunctioning of the pump and fluid flow control arrangement shown inFigure 6,

Figure 9 is an enlarged view of the fluid pump construction illustratedin Figure 3,; and

Figure 10 is a diagrammatic chart illustrating the characteristics of atypical high speed, high torque induction motor and fluid resistance oforifices of various sizes.

In the utilization or operation of comparatively large machine tools andespecially those of the character having a relatively movable orrotatable work supporting table,. the movement or indexing of such worksupporting table to successive positions has presented manydifficulties. In large machines the work supporting table may have aweight of several thousand pounds which is augmented by the weight ofcastings, forgings or metal pieces carried thereby upon which workoperations are to be performed. In carrying on successive machiningoperations upon work such Indexing is usually accomplished.

latching means has been comparatively shorty Applicant's presentinvention is inclusive of a simplet yet effective means utilizing a highslip,"

high torque motor operable to move the table quickly from station tostation in combination with a counteracting force adaptable'to resistthe inertia of the table and work supported thereby when the tableapproaches indeXillg position so that the indexing or latching means isnot subjected'to any appreciable force and the life of the latchingmeans therefore greatly prolonged. Referring to the drawings in detailthere is illustrated in Figure 1 a machine tool of a characterparticularly adapted for performing drilling or similar machiningoperations upon pieces of work. The machine is inclusive of a baseportion or frame Ill upon which is mounted an upright frame l2. The baseportion it supports a work carrying table or platen M which revolvesabout a central axis to move the work to successive stations wheremachining, drilling, reaming orother operations may be performed uponthe work. The work pieces are mounted upon suitable fixtures indicatedat i5 mounted upon the table [4. In the machine illustrated, the uprightframe [2 is formed with a pair of vertically disposed parallel ways l6upon which is slidably mounted a tool carrying head or member i l. Thehead I l is inclusive of a housing l8 which encloses and supports aplurality of tool actuating gears or mechanism (not shown) foroperatingrotatable tools, for example, drills, reamers or the'like. Ina machineof this character it is usual to provide several stations upon which thedifferent machining operations may be carried on simultaneously upon aplurality of work pieces so that the rotatable tools for performingseveral machining operations are arranged in groups, one for each workperforming station, for operation upon several pieces of work. Mountedupon the tool supporting head or memher I! is an electrically energizedmotor 19 which serves to rotate the several tools carried'by the headIT. The head H is moved vertically to bring the tools into and out ofengagement with the pieces of work by hydraulic or other suitable means(not shown).

As shown in Figure 1, the head IT is provided with depending shafts orpilots 2| which are adapted to cooperate with guide bushings 22 carriedby the work suporting fixture 15 or by the table I l so that when thetool carrying head moves downwardly to bring the tools into engagementwith the work pieces, the pilot pins are received into the bushings 22to prevent relative rotatable movement of the work table during drillingor other machining operations.

In machines of the character disclosed in Figure 1, the table It! ismoved or rotated after each 7 carrying table to various positions and tomeans 1' shaft 5].

4 for controlling the movement of the table so that damage or wear ofthe table locating or indexing means is greatly reduced or eliminated.

As particularly shown in Figure l, the table M is formed with a centralhub portion 23 which is centraly bored to accommodate a pair ofantifriction bearings 24 and 25 preferably ofthe ball type and which arespaced by means of a suitable colar 2E. The frame It is formed with acentral pedestal portion 21 which is bored to receive a cylindricaltenon 28 formed upon a plate 29 which is secured by means of screws 30to'the pedestal 2?. Associated with the plate 29 is an upwardlyprojecting shaft portion 31 upon which is fitted the bearings 24 and 25.The upper end of the shaft 3| is threaded as at 32 to accommodate aretaining nut 33 to hold the bearings 25 and 25 and the spacing collar26 in position in the hub 23 of the table. An access opening in theupper central portion of the table M is nor-. mally closed by means ofan escutcheon plate 35 to prevent the ingress of dirt and foreign matterin the bearings 24 and 25.

Mounted upon the base frame Ill is an annularly shaped member 36 whichis provided with a recess adapted to receive a ring 31 of hardened metalor the like. an annular recess adapted to receive a similarly shapedmember 38 also of hardened material. Disposed between the members 31 and38 is a plurality of bearing balls. 39 or other suitable antifrictionbearing means, the latter being adapted to support the table I l. Thebearing balls 39 are maintained in a suitable race way formed by annularmembers 49 and ll which are mounted upon the ring 36. The bearing means39 supports the weight of and resists the downward thrust of the tableand the work supported thereby while the bearing means 24 and 25 at thecenter of the table properly and accurately I position the table forrotation about the axis of shaft 3!.

The driving means for the table M is inclusive of an electricallyenergized motor 45 mounted upon a plate 46, the latter being secured tothe base frame I 0 of the machine as shown in Figure 3. In thearrangement illustrated, the motor shaft 48 projects upwardly and into acentral bore formed in a shaft 39, the latter being secured to the shaftby means of a pin 50 or other means. The shaft is is journaled insuitable bearings indicated at 51 and 52. Formed on the shaft as is apinion 54 which meshes with a driven gear 55 mounted upon a'tenon '55 ofa The axis of the latter being'parallel with the shaft 48. The shaft 5!is journaled at its upper end in a bearin or bushing59 and is journaledat its lower end in a ball bearing 69 which is supported upon the frameH) of the machine by means of an annular plate 6! held in place by meansof screws 62. tremity of the shaft 57 is formed with teeth to provide adrive pinion 53 which meshes with a ring gear as secured to the table14. Thus rotation of the motor shaft 48 drives the shaft 57,

rotating pinion 63 to revolve the work supporting table. Id.

The base frame H3 is provided with a pair of aligned openingsaccommodating bearing sleeves 67 and 68 within which is journaled ashaft 63 arranged with its axis parallel with the shaft 51.

. The shaft 5'! has an intermediate portion formed shaft 59 is a member73 having aportion 14 of lesser diameter than the lower portion of mem-The table I4 is formedwith The upper exbehwand upon which is mountedthe. gear TI. The" gearis fixed to member: 13 by means. ofdiametricallyopposed keys 15,-. the.- portion 12' of" shaft 69 beingprovided with-a2 recess adapted to receivethe extremity of alockingscrew 19"- carried in a suitable threaded bore in member 13" for fixedlysecuring the latter to the shaft. The shaft 53 is held in its bearingsby'eng'age-- ment ofmember-"l3 engaging anupwardly extending bossportion- 80 formed on the base frame- III.

The lower'portionof the shaft BS is of reduced diameter as indicated at83 which is adapted to receive sleeves 84 and 85which are formed with.suitable cams or projections 82. for actuating electric: circuit controlmechanism. The cam.

membersor sleeves; 84 and 85 are-rotatably: adajusta'ble upon the-shaft:portion; 83 r and are: held in adjusted position by means" ofsetscrews8|, so that" the proper timing ior'actuation of'the. electric switchesmay be obtained. The cam. sleeves are supported upon the shaft portion83 by means of a collar'iifi which is secured. to the shaft" by. meansof a pin 81. The circuit controlling switches 80 and are mounted upon asub-frame 9I- which is secured to the baseframe I0. Each of the'switches89 and 30 iscontained in a suitable housing, the switches being providedwith rollers or members 92 and 93, which are arranged tobeengagedbyprojections 02' on sleeves '8'4 and 85 to control the circuit: of themotor 45'.

The member I3 is formed with a notch or recess 90 having a radiallydisposed wa1l0I which forms: a ledge or abutment which is adapted forengagement with an indexing pawl or member 98. The pawl 98 isconnectedby means of a pivot pin 99 carried in a clevis-like member I00which is formed with a cylindrical tenon I03 which is contained in acylindrical recess formed in a member I04. The exterior surface ofmember' I04 is threaded and adapted to extend into a threaded borecontained in a housing plate I01. Themember' I04 is enclosed with a capor closure I08 which is internally threaded and adapted to be" receivedupon the threaded portion of member I04. The end closure I03 is providedwith a recessor annular-groove adapted to receive a sealing gasket IIO;Thus when the closure I08 is threaded on to the member I04, the gasketIII) is compressed against the exterior surface of frameplate I0! to.seal the interior of cap I 08, the latter! also. serving as a lock nuttosecurely hold. the member I04 in the plate I01. The tench" I03 isthreadedto receivethe threaded end of a bolt. IJI2. to secure tenorrI03. to the member I04- The. purpose of" tenon I03- and bolt H2. is toadjust-the member I00 rotationally about its longitudinal axistoproperly align the pawl 08 with the recess 96 in cam member I3. Themember I00 is fitted with a block or abutment III which is secured inplace by means of ascrew I I5 which isarranged to contact therearsemi-cylindrical surface II6 formed upon the end of. thelatch or: pawl08. The pin 99 carried by the latch or pawl 90 extends into openingsII'I formed in the pro-- jecting' portions of. member I00; the diameteror. the openings being larger than. the diameter of the pin 39 so thatthe latch or pawl 08 is capable of limited relative movement withrespect to the. member I00. The hardened block; or abutment lid isarranged to be contacted or engaged by the surface: IIG of latch 98without the pin 93 contacting the bounding walls. of openings III.Through this arrangement, the thrust ofthe table indexing operationwhiclLmay-i lietrmismitteii' longitudinally ofthe latch 50 and in.- a;direction: toward the abutment block I is absorbed. and

resisted by the latter: to: obviate-theawcan of. the pin 00 0i walls-ofthe openings I'IJ: Thuszdurin'gindexing operations, when: the latch. 38:is-suh.-. jected to thrust, thehardened bloclc llIfig willzah-l. sorbsuch thrust and' thus greatly. prolong thelife of" the indexingmechanism.

The frame plate I01 is secured; to a. member." E20 forming-part of theframe I0vof theemachine; The member I20 is bored I';o-receive.-a.bushing IZI within which is disposed a cylind'rical moms. ber I22, thelatter being centrally-bored.tel-ac commodate a plunger: I23. Theplunger I2; is".

urged outwardly underme influence oi-"an; exe-- pansive coil spring"or'other resilient means-.- In; contained within the bore formedin.-the;.member I22. The extremity of the plunger; I23 is an.-

ranged to contact or engage the pawl orrla'toh: 98' as shown in Figure2, which serves: to" urge the;

pawl into contact with the cam or cam wheel I36v for indexing orpositioning the work: supporting; table I4. The latchis' guided orsupportedada jacent' the plunger I23 by means'ofaledgerpon tion I25associated with member I22; The bush. ing I2I is integrally formed witha headportion. I2? which is secured to frameamember I20- by means ofscrews (not shown)".

Means are providedfor reacting against. rota: tion of or absorbing thetorque of the motor so as to efiiciently and efi'ecti'vely control 'theStop'- ping and indexing of the work supporting table. In the preferredembodiment Ihaveshownafluid: resistance means for accomplishingthispurpose and function. To this end there is-mounteduponv the shaft orsleeve 49, carried by motor shaft, a member I secured thereto by meansof a key (not shown). Also connected to member I30 isa gear I32 which issecured to the member I30 by suitable securing screws I33 orothersuitable means.

Mounted upon the plate 46, which carries the" motor 45, is a member I36.The member I36 is formed with elongated slots I3I at-its upper-portionand a third elongated slot I38 at itslower: portion which are adapted toreceive securing means in the form of screws I39 and I40. By'manipulation of the screws I39 and I40-themember I35 may be adjustedwith respect to the sup-- porting frame or plate 46 to bring the gearsI32 and I into proper enmeshment.

Associated with the member I36v is a housing; forming a receptacleadapted to contain. oil or other suitable fluid". Disposed within. thehousing I4] is a fluid pump I41 which may be of any" suitable character.trat'ed the pumpis of the so-called gear type in which rotating meshinggears serve to move-or convey fluid through the pump housing I48. Thereceptacle or housing MI is provided with'a suitable cover plate I49.The plate I43 is held inposition by means of securing screws (notshown).

The pump I4! is provided with a: pair of vertical shafts I53 and I 54which are-arranged in parallelism. The shaft I53 extends exteriorly ofthe housing MI and upon which is mounted a gear I55, the latter being inmesh with the teeth- I of the gear I32 carried by the motor shaft. The

gear I55 is fixedly secured to the shaft I53 bymeans' of a suitable keyI55. The shaft I53 extends through asuitable stufiing gland or sealingmeans contained within a bushing I51, the latter being fixedly securedtothe housing cover In? the embodimentillusplate I49 bysuitable means.Within the pump housing M8 there is fixedly secured to shaft I53 atoothed rotor or gear Its which meshes with a driven rotor or gear It!mounted upon the shaft I54. The pump housing its is provided with apassage or opening H52 formed in a fitting I63 which is threaded into abore in the depending portion Hid of the pump housing. A dust or channelW is in communication between the opening I52 and the chamber housingthe pump gears I65 and ifil. This duct N55 is of larger diameter thanthe opening or passage ifiE and disposed within the channel its is acheck valve I67 preferably of the ball type. The housing it! ispreferably filled with oil or other suitable fluid and I have found itpreferably to have the pump mechanism immersed in the fluid, a desiredfluid level being indicated at Hi8.

While the pump mechanism may have a natural slip that is, the parts orelements have sufiicient clearance for operation which will permit aminute leakage of fluid from the pressure siderand'this leakage may beutilized to control the motor speed, I have found that for mostsatisfactory-operation, such fluid slip is inadequate. I have thereforeprovided a fluid metering orifice 369 for predetermining a now of fluidthrough the pumpand thus the absorption of motor torque for regulatingthe speed of the motor.

The operation of the form of my invention shown. in Figures 1 through 4is as follows: In moving the Work supporting table it from one stationto a succeeding station the operator may initiate an indexing operationof the work supporting table by manually closing a suitable switch (notshown) which completes an electric circuit through the table actuatingmotor 55, or in; certaintypes of machine tools the motor circuit rnay beclosed by means of a circuit closing switch automatically operated bymeans associated with the vertically movable tool carrying head H. Inthe latter arrangement, the switch may be moved to circuit closingposition by the retraction or upward movement of the head ii,aftercompletion of a work performing operation.

Upon energization of the motor 55 by either of the above mentionedmeans, the shafts 2S and 49: are rotated, thus rotating gears 5d and 55to cause comparatively slow rotation of shaft 5? by reason of thedifference in sizes of gears 54% and 55. The gear 63 at theupper end ofthe shaft til-being in mesh with the ring gear 54 rotates the tablel iabout the axis of shaft 39. Simultaneously the gear it formed on shaft5? intermediate its ends being in enmeshment withthe larger gear-Hcauses rotation'of shaft 'l2- at a greatly -reducedspeed compared to thespeed oi shaftjl. ."In the-embodiment illustrated, the work-supportingtable I d is arranged to have four indexpositions or stations which arespaced 90 degrees apart, the gears iii and H being so proportioned-vthat with each movement of the table through 90 degrees, that is, fromone station to a successive station, the gear ll and cam member 73 willmake one complete revolution.

During rotation of the motor shaft 38 in a direction to revolve the worksupporting table Hi in a forward direction, the gears lSZ and 55 causerotation of the pump rotors or gears E63 and It! in a direction to admitfluid or oil from the supply in receptacle or housing it! throughopening I62 and tube I55 upwardly past the ball checkvalve it? into thepump chamber containingathe pump, rotors thence, through an outletpassage 20B and. into the receptacle MI. As-the pump is rotating in adirection to freely admit fluid into the pump chamber through thepassages IE2 and I65, no appreciable resistance to the operation of themotor is offered by the pump struc-, ture, so that the work supportingtable 14' may move comparatively rapidly toward the next station orindex position.

As has been previously mentioned herein the work supporting table andthe work constituting the load to be moved by the motor 45 very oftenweighs several thousand pounds which presents a very high inertia factorto be overcome in bringing the Work supporting table to rest. Theindexed position of the table must be accurately determined in orderthat the tools carried by the tool carrying head I? may be brought intoproper V engagement with the work carried by the table next station orposition of rest, a projection 82 on the cam or sleeve member 85 isadjusted on the shaft 12 so that when the cam member or disc i3 isapproximately in the zone wherein the latching pawl or indexing abutmentis in position to engage in the recess 96 formed adjacent the abutmentwall 97, the roller 93 of the switch will be actuated by contact withthe projection to reverse the current flow through the motor 45. Thisreversal of current temporarily acts-as a brake on the motor to quicklybring the table M to a static position ahead of its normal indexposition. As soon as the table comes to a position of rest, the reversalof motor 45 initiates rotation of the table in a reverse directiontoward indexing position, i. e. in a direction to bring the abutment orwall 91 into contact or engagement with the extremity of the latchingpawl or indexing arm 98. As soon as the motor comes to rest and prior toits reverse rotation, the pump rotors also cease rotation so that no oilor fluid is mov: ing through the fluid pump. At this moment the ballcheck valve moves by gravity to its closed position. Reverse rotation ofthe motor causes a corresponding reversal of movement of the pump rotorsl5! and I62 and thus reverse the direction of flow of oil or fluidthrough the pump.

As the ball check valve I6! is in closed position it prevents the flowof oil from the pump chamber through the passage 162. The oil or fluidis then extruded through the metering orifice P69 or through the naturalslip of the hydraulic pump thus absorbing a major amount of torque ofthe :motor as the cam member 13 is moved in a reverse direction towardindex position. This absorption of motor torque greatly reduces thespeed of the motor inv a, reverse direction, the speed being dependentupon the rate of fluid fiow.

through the metering orifice l 69. As the torque of the motor is veryhigh under a low speed condition, the table will move slowly in areverse direction until the abutment wall 91' of cam '13 engages theextremity of the latch pawl 98 to index or predetermine the position ofthe work supporting table.

At the time the switch mechanism 90 effectseither by the actuation of amanual switch or by an automaticswitch.

In the system and apparatus of my invention :1 utilize a motor 45 of theinduction typ having high torque, high slip characteristics, although adirect current or other type of motor having these characteristics maybe employed. In motors of this character, the torque factor increases orrises as the motor speed is reduced. Thus the motor torque operative todrive the table or load is exceedingly high so that normally the motorwould quickly rise to its top speed. This condition obtains when themotor is rotating in a direction to advance the work supporting tableand provides a means for rapidly moving the table and work carriedthereby to the next station. The fluid resistance means, which comesinto operation upon reversal of the direction of .rotation of the motorto finally index the table,

absorbs most of the motor torque and thus prevents the motor fromdriving the table in a reverse direction at a high speed. Bypre-determining or metering the fluid by utilizing natural slip of thefluid pump .or ,flowof fluid through the metering orifice I69 or both,the rate of fluid flow determines the rate of rotation of the motor sothat the work supporting table is slowly moved into complete indexedposition without causing shock, wear or damage to the indexing pawl orlatch mechanism.

At the time of completion of an index cycle the safety switch 89functions to prevent inadvertent closing of the motor circuit so thatthe work supporting table remains in index position until .thetoolcarrying head I! has been retractedfrom the work. After the head I! isretracted, subsequent movement of the Work supporting table .may be hadeither by a manual switch means .or

automatic switch means controlled by movement .of the tool carrying headtoits initial position.

the torque absorbing factors of meteringorifices of the differentdiameters specified in inches.

Thus by referring to Figure '10, a metering orifice having a diameter ofone hundredth of an inch as indicated at d will admit passage of fluidat a comparatively slow rate-thus absorbing most of'the motor'torqueresulting in a comparatively slow motor speed. It will be-seen fromFigure that while the motor torque is comparatively .high at aslowspeed,the fluid resistance'offered byfluid flowing through a metered orificeoffers a corresponding-lyhigh resistance to the motor so that by thismeans an eflective speed control may be attained. By varying or changingthe size of the fluid orifice the speed of the motor may be changed. v

Figure 10 also exemplified a specific operating condition of themotor,'load and fluid speed control means of my invention. The curvedesignated Motor speed torque curve illustrates a typical speed, torquecurve of a motor delivering maximum'torque at zero speed. The curvesd-I, d-Z, 11-3 and (2-4 illustrate the fluid absorption curves fordifferent rates of fluid flow or fluid metering through the pump. Thevertical line AB represents diagrammatically the torque in footpoundsrequired for rotating the table or moving the load at a motorspeed of approximately 360 revolutions per minute. Consider-"ingparticularly the formof the invention .dis-

minute.

10 closed in Figures 2, 3 and 7, wherein the direction of rotation ofthemotor is reversed to bring the table to indexed position, the motorand load come to rest at a point beyond .or in advance of the indexposition. When the motor comes to rest, the ball check or valve I61falls into contact with its seat and closes the passage I62 in thefitting I 63. Immediately upon rotation of the .motor and the fluid pumpin a reverse direction,

diameter absorbs torque from the motor very rapidly as the speedofthemotorincreases. This absorption factor increases .until the length.ofthe line ,CD equals the torque requirements to move the table or load inthe reverse direction. The torque in foot pounds represented by the lineCD is equal to the torque represented bythe line AB. Thus it isto benoted that thedistance of the line CD measured horizontally from thevertical base line at the left indicates that the table or load will bemoved in a reverse direction at approximately a speedof revolutions .per

An orifice size is chosen which will=re- .duce the motor speed lowenough asnot to result in shock .or damage to thetable indexingmechanism. II" extremely heavy loads are required to be moved veryslowly, a smaller diameter-metering .orifice may be utilized. I havefoundthat thisarrangement is extremely valuable as a motorcon- 'trolbecause it makes possible the utilization of a motor capable ofdeveloping its highest torque at zero speed for actuating or movingcomparatively great loads ata controlled speed simply by regulating therestriction of fluid flow through the pump.

A modified form .of table indexing mechanism and fluid resistance meansare shown inFigures 5, 6 and 8 of the drawings. The indexingmechanismillustrated in Figure 5 is inclusive of cam member 13' formed with arecess or kerf I12 ..J'ection I15 arranged .to snugly fit into recess Infor positioning or indexing the work supporting table. The pawl memberIi l is pivotally mounted upon a pin ITI carried by a fitting I'ISmounted upon member I241. The latch pawl I14 is provided with apin Iconnected to one end of a contractile spring I8 I, the other end of thespring being secured to afixed portion of the machine by means of a pinI82. The spring IBI provides a resilient means for yieldingly urging thelatching member or pawl I74 toward the cam member '73.

Means is provided for withdrawing the latching pawl IM from engagementwith the cam member I3. In the embodiment illustrated, this means is 'inthe form of an electrically actuated solenoid actuated valve mechanism295.

a pin I92 which projects through an opening in the link I89 to establisha pivotal connection between the link and the armature I89. The otherend of the link extends in to a recess formed in the latch member I12.The portion of the link I89 extending into the recess I93 is slotted asat I94 to accommodate a pin I95 carried by the pawl member I14. The pinI95 and slot I94 provide a lost motion connection between the pawlmember I14 and the link I89 so that the link may move a predetermineddistance before withdrawing the pawl from the recess I12 and to permitthe pawl to be moved into the recess I93 under the influence of springNH.

The arrangement of fluid pump and fluid flow control mechanismespecially adapted for use with the form of indexing mechanism shown inFigure 5 is illustrated in Figure 6. In this form of arrangement thefluid pump I48 is disposed in a housing IfiI' similar to the fluidcontaining chamber I4I shown in Figure 9. The pump shaft I53 supports agear I55 which meshes with a gear I32 mounted upon the motor shaft as inthe form of the invention shown in Figure 3. The pump construction IE8is of the rotating gear type and is provided with an inlet passage 299and an outlet passage 29I, the latter being fitted with a tube or pipe202. The chamber or reservoir formed by the housing I4I contains asupply of oil 203 or other suitable fluid which may be acted upon by thepump I98. Means are provided for interrupting the flow of liquid throughthe pump in order that the resistance of the fluid may be utilized toabsorb torque from table actuating motor. In the embodiment shown inFigure 6,'this means is in the form of an electrically This mechanism isinclusive of a solenoid 299 having a core 291 to the lower end of whichis pivotedly connected a link 208. The link is threaded as at 299 into athreaded bore formed axially in a cylindrical valve member 2I0. Theinterior of the valve is bored as at 2 I2 to accommodate a resilientmeans or spring 2H3, the upper end of which is secured to the valve 2I0by means of a pin 2I5, the lower end of the spring being secured to arelatively stationary fitting 215 the latter being securely fastened tothe bottom portion of the housing I4 I by means of bolts 2I1. Thefunction of the resil- "ient means or spring 2M is to urge the valvemember 2I0 to its lower-most position as shown in Figure 6. Surroundingthe valve 2I9 is a cylindrical member 2I8 mounted upon a plate 2I9. Theplate 2 I9 also supports the solenoid mechanism and is secured to thewall of the housing I4 I by screws 220 or other suitable means.

The member H8 is formed with a radial channel or passage 22! into whichis threaded a fitting 222 for connecting the tube 292 with the member 2l8. The relationship of the pump, valve mechanism and communicating tubeis shown diagrammatically in Figure 8.

The operation of indexing the work supporting table by the motor and thecontrol means therefor as shown in Figures 5 and 6 is as follows:

Electric current is supplied to the motor to rotate the table in aforward direction toward the next indexed position. The current may besupplied by the operator closing a manual switch to complete the motorcircuit or by an automatic switch controlled by the position of the toolcarrying head I1. During a major part of rotation of the work supportingtable from one station to the succeeding station, the solenoid 299 isenergized through circuit controlling devices to elevate the valve 2) toa position above the radial channel 22I so that the flow of fluidthrough the pump I48, tube 292 and passages 22I is unrestricted so thatthere is no appreciable motor torque absorbed by the pump structure andthe torque used to rotate the table at comparatively high speed. As thework supporting table approaches the next successive index position, theswitch means 99 is arranged to de-energize the solenoid 209 as well asto energize a delayed action relay (not shown) of conventional design,the latter mechanism being employed to interrupt the motor circuitapproximately at the time of completion of the indexing cycle. Thedeenergization of the solenoid 296 permits the sleeve valve to move toits lower-most position under the influence of spring 2M so as to checkthe flow of fluid through tube 202 and passage 22I into the fluidsupply. As soon as valve 2I0 interrupts fluid flow, the only fluid whichmay pass through the pump is that permitted by a metering orifice 224 orby the natural slip of the pump so that an immediate torque absorptionmeans is impressed upon the motor by the almost complete obstruction ofthe flow of fluid through the pump. This means causes the motor torapidly decrease its speed. This decrease in speed of the motorcorrespondingly reduces rotation of the work supporting table down to avery low speed so that when the recess I12 in cam 13' is in a positionto receive the looking or indexing pawl I15, the work supporting tablewill be brought to rest. Approximately at the time that the indexingpawl I15 enters the recess I12 in cam member 13, the delayed actionrelay interrupts the motor circuit to completely de-energize the motorat the time final indexing takes place.

By means of this system and method of motor control, the work supportingtable may be rapidly moved by the motor traveling at a high speed to apoint near the next station or index position. At this point the motorand work supporting table are rapidly decelerated until at the finalpoint of indexing, the table is moving comparatively slow so that thereis little appreciable shock to the indexing mechanism when the indexingposition is reached. Thus by this means the indexing mechanism isrendered capable of long life and is not liable to excessive wear.Through the utilization of the motor control arrangement of myinvention, the time required to move a work supporting table from onestation to a succeeding station is greatly reduced.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than is herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

What I claim is:

1. In combination, a frame; a work supporting table arranged formovement to two or more positions relative to said frame; anelectrically energizable motor having high slip, high torquecharacteristics; means arranged between the motor and the table fortransmitting power from the motor to the table; indexing means fordetermining relatively stationary positions of the table; torqueadsorption means including a fluid pump connected to and driven :by saidmotor, valve means for rendering said torque absorption means eifectiveto reduce the speed of said motor and table while said motor isenergized, and means dependent upon the relative position of the lockingmechanism; torqueabsorption means including a fluid pump connected toand driven by said motor, and valve means for rendering said torquabsorption means eff ctive while said motor is energized to reduce thespeed of said motor and table when said tableap-proaches an indexposition, and means dependent upon the relative position of the tablefor controlling the operation of said valve means.

3. In combination, a machine having a rotatable table; an electricallyenergized motor having high slip, high torque characteristics; powertransmission mechanism disposed between said motor and said tablewhereby the table is driven by the motor; means for indexing the tableselectively in several positions; fluid torque absorption meansincluding a gear pump connected to and adapted to be driven by saidmotor; valve means for restricting fluid flow whereby torque is absorbedfrom the motor to reduce the speed thereof as the table moves adjacentan index position; means for controlling said valve means, and ametering orifice associated with said fluid torque absorption means toprovide for minute flow of fluid to cause said motor to operate at aslow speed as the table approaches index position.

4. In combination, a machine having a rotatable table; an. electricallyenergized motor having high slip, high torque characteristics; powertransmission mechanism disposed between said motor and said tablewhereby the table is driven by the motor; means for positioning thetable selectively in several positions including a cam associated withsaid power transmission mechanism and movable simultaneously with saidtable; said cam having an abutment; means adapted to be engaged by theabutment on said cam to determine a table position; fluid torqueabsorption means including a gear pump connected to and adapted to bedriven by said motor;

valve means for restricting fluid flow through the torque absorptionmeans whereby torque is ab sorbed from the motor to reduce the speedthereof; and electrically controlled means for rendering said valvemeans effective, and a metering passa e in said fluid torque absorptionmeans providing for reduced flow of fluid to maintain a relatively slowcontrolled speed of the motor until the table attains a selectedposition.

5. In combination, a machine tool having a rotatable work supportingtable; an electrically energized induction motor having high slip, hightorque characteristics; gearing disposed between said motor and saidtable whereby the table is driven by the motor; means for positioningthe table selectively in several positions including a cam associatedwith said gearing and rotatable simultaneously with said table; said camhaving an abutment; a pawl adapted to be engaged by the abutment on saidcam to determine a table position; torque absorption means including afluid pump connected to and adapted to be driven by said motor; valvemeans for restricting fluid flow through said pump whereby a sume*torque is absorbed from the motor to reduce the speed thereof; meansdependent upon the'rel'ative position of the table for controlling theoperation of said valve means, and a metering orifice providing forlimited flow of fiuid'whereby said energized motor operates with hightorque at relatively low speed at the time the pawl engages saidabutment.

6. In a machine tool in combination, a work supporting table adapted tobe moved to several stations; an electrically energizable motor havinghigh slip, high torque characteristics; power transmission gearingwhereby said table is adapted to be riven by the motor; indexingmechanism for positioning the table at each successive station; torqueabsorption means including a fluid pump connected to and driven by saidmotor; a reservoir containing a supply of fluid for the pump; valvemeans for restricting the normal flow of fluid through said pump; ametering orifice bypassing said valve means to permit limited flow offluid through said pump when said valve is in closed position wherebythe speed of said motor is reduced through the absorption of torque fromthe motor under the influence of restricted fluid flow through saidpump, and means set into operation upon the table approaching a. stationfor actuating said valve means, said motor being electrically energizeduntil said table attains an indexed position.

'7. In a machine tool in combination, a revolvable work supporting tableadapted to be moved to several stations; an electrically energizablemotor having high slip, high torque characteristics; power transmissiongearing whereby said table is adapted to be driven by the motor;indexing mechanism for positioning the table at each successive station;torque absorption means including a rotary fluid pump connected to andadapted to be driven by said motor; a fluid reservoir surrounding saidfluid pump and containing a supply of fluid; valve means for restrictingthe normal flow of fluid through said pump; a metering orifice bypassingsaid valve means to permit limited flow of fluid through the pump whensaid valve is in closed position whereby the speed of the electricallyenergized motor is reduced through the absorption of torque from themotor under the influence of restricted fluid flow through said pumpuntil said table attains an indexed position, and electricallyenergizable means set into operation upon the table approaching astation for actuating said valve means.

8. In a machine tool in combination; a revolvable work supporting tableadapted to be moved to several stations; an electrically energizablemotor having high slip, high torque characteristics; power transmissionmeans asociated with said motor whereby said table is adapted to bedriven by the motor; indexing mechanism for positioning th table at eachsuccessive station; fluid torque absorption means connected to andadapted to be driven by said motor; a reservoir for said torqueabsorption means containing av supply of fluid; a check valve associatedwith said torque absorption means adapted to provide for substantiallyunrestricted flow of fluid when the motor is rotating in one direction;said check valve aranged to restrict the flow of fluid through said pumpwhen the motor is electrically energized for rotation in a reversedirection, and means bypassing said valve for conveying fluid throughsaid pump in restricted quantities whereby the flow of fluid throughsaid bypass means controls the speed of rotation of the motor andrevolvable work supporting table during reverse rotation to an indexposition, and means associated with the table for efiecting the reversalof said motor. 5

THOMAS L. HALLENBECK.

REFERENCES CITED The following references are of record in the 10 fileof this patent:

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